Anionic surfactants are often used for cleaning and pharmaceutical purposes because of their strong surfactancy and foaming property. However, they are rarely ingested orally, the skin is a part of the human body most affected by surfactants. Barrier function of the skin is very strong, but the anionic surfactants can cause serious damages to it. Recently, amino acid-based surfactants have attracted attention as a safer option owing to their biocompatibility. Cytotoxicity examinations revealed that the amino acid-based surfactants are superior to sulfate-based surfactants. However, a systematical and comprehensive study related to the effect of these surfactants on skin barrier function has not yet been reported. In this work, skin permeation test using the skin of hairless mice and HPLC method is carried out. The material transmission speed through skin in a steady state was different between each surfactant treatment. We performed a comprehensive analysis of the effect of surfactants on skin barrier function and defined Transmission Index as an index for the degree of effect of surfactants. Glutamate series amino acid-based surfactant were effective to Transmission Index and we guessed the cause was due to adsorption. Based on the finding this study, we suggest using adsorptive property as a measure to the effect on the skin barrier function.
Keywords: Anionic surfactant; amino acid-base surfactant; fatty acid; skin permeability.